Metric System

History Of Metric System The metric system was invented by the French around 1795 This was a primitive form of the metric system that did not deal with as many measurements as we have now In 1960 an improved version of the metric system was devised, known as the “International System of Units” (SI) The metric system is a accepted version that is based on the multiples of ten. The United States is the only country in the world that does not use the metric system.

Reasons for Using Metric System Easy to use, based on multiples of ten Standard system for every country in the world except for the United States Scientists use the metric system and only the metric system when doing experiments

Base Units Each type of measurement has a base unit Length-Meter Mass-gram Time-Second Temperature-Kelvin Volume-Liter

Prefixes The SI system is easy to use because it is based on multiples of ten Prefixes are used with the names of the units to indicate what multiple of ten should be used Ex. Kilogram, centimeter, milliliter

Chart of the Prefixes and Conversions

Measuring Distance The size of the unit you measure will depend on the size of the object being measured Ex. To measure a shirt button you would use centimeters, you would also use centimeters to measure a pencil. What would you use to measure the distance from here to Madison

Measuring Distance (Cont.) By choosing an appropriate unit, you avoid large digit numbers and numbers with decimals 21 km is easier to deal with than 21,000 m 13 mm is easier to deal with than 0.013 m

Measuring Volume The amount of space occupied by an object is called its volume To measure volume of a solid object you take the measurements of its length, width, and height and multiply all of them together If you were measuring a brick you would probably measure in centimeters, and therefore your label would be cm3, the reason for this is because when you multiply, you add exponents.

Measuring Liquid Volume We just talked about how to measure a solid volume, but how do you measure a liquid volume, a liquid has no sides to measure. In measuring a liquid, you are measuring the capacity of the container that holds that amount of liquid. The most common units for expressing liquids are liters and milliliters

Measuring Matter A table tennis ball and a golf ball have the same volume, but if you pick them up, you will notice a difference. The golf ball has more mass. Mass is a measurement of the quantity of matter in an object. Matter is what a physical object is composed of

Density Density is the mass per unit volume of a material You find density by dividing an object’s mass by the object’s volume. So, D=m/v One key thing to remember is that volume is reported in cm3 The density of pure water is 1 g/ml If an object has a density of less than 1 g/ml it will float If an object has a density of more than 1 g/ml it will sink

Measuring Time Time is the interval between two events The SI unit for time is seconds

Measuring Temperature Temperature very simply is the measure of how hot or cold something is The SI unit of temperature is the kelvin (K) 0 on the kelvin scale is the coldest possible point, also known as absolute zero

Temperature in the Lab Most thermometers are in Celsius, but as stated before scientists use Kelvin to report temperature, so to convert from Celsius to Kelvin just add 273, and to convert from Kelvin to Celsius, subtract 273.

Converting from Celsius to Fahrenheit and vice versa Celsius = (5/9) x (deg F-32) Fahrenheit = (1.8 x deg C)+32

Some conversions to add to your notebook 1 mL = 1 cm3 1 inch = 2.54 centimeters 1 pound = .5 kilograms 1 mile = 1.6 kilometers 1 gallon = 3.8 liters 1 gallon = 8 pints 1 meter = 39.37 inches

Monday Sept. 9th Do Now Convert the following, 34.5 mm = _____________ m 23.6 kg = _____________ mg

Scientific Notation Scientific notation is simply a method for expressing, and working with, very large or very small numbers.  It is a short hand method for writing numbers, and an easy method for calculations.  Numbers in scientific notation are made up of three parts: the coefficient, the base and the exponent.

Format 5.67 x 10 -5 coefficient base exponent

Converting Scientific Notation The number, .00000000000000235, would be difficult to type into a calculator, because you may miss some zeros, so this is where scientific notation comes in handy. This number can be rewritten as; 2.35 x 10 -15 This format is much easier to type into the calculator and not miss zeros

Scientific Notation Rules: Only 1 digit before the decimal point Multiply the number by a power of 10 Example: Write 34,000 in scientific notation 34,000 = 3.4 x104 Why do we use this? It’s shorter and easier!

Scientific Notation Examples 4,100,000 = _______________ 345,600,000,000 = _________ 0.0456= ________________ 0.00000012=____________ 0.00305= ____________

Scientific Notation Examples